The first stretch of a $2 billion, 28-mile tunnel being bored through the rock underneath the streets of Indianapolis will soon be filled with millions of gallons of sewage.

The thought of what is essentially a massive underground urban toilet might generate more than a few "ewws" and turned up, or plugged, noses.

But for Mike Miller, this 11-mile stretch of the DigIndy project — arguably the most significant environmental project ever undertaken in Indianapolis — is a thing of beauty.

"It's very surgical," said the project engineer with Citizens Energy Group. "The science behind it and what it will do for Indianapolis is really exciting."

On Dec. 29, the first 11 miles of the 18-foot wide and 250-foot deep tunnel will come online. What that means is that the next time after the new year that the city sees rain, much of the sewage and storm water that normally overflowed into the White River and other city waterways will instead dump into the tunnel.

That's a huge win for the notoriously polluted White River, but one that comes with a cost — and not just the one being paid by Citizens rate-payers. DigIndy also has necessitated various road closures to connect the pipes at street level with the underground work. And perhaps the most noticeable one is about to begin.

Starting in January, Meridian Street will be closed at 28th Street for 10 months — though officials say the construction chagrin will all be worth it in the end.

"When Meridian Street is closed for any amount of time, people notice," said Deputy Mayor Jeff Bennett of Indianapolis Mayor Joe Hogsett's office. "So anyone who didn't know about this project before will certainly know come January."

"But this is the next step in what will be a transformative project for our infrastructure, for the White River, and transformative for the city as a whole," he told IndyStar. "I just can't overstate the potential of DigIndy."

Michael Miller looks at the structures in the Southport DRTC Pump Station, Monday, Sept. 11, 2017, while standing in the cavern. The pump station cavern connects to the tunnel system.
Kelly Wilkinson/IndyStar

The Southport DRTC Pump Station is seen, Monday, Sept. 11, 2017, through the grate of the cage that transports people down into and out from the tunnel. The large pump station cavern, seen here, connects to the tunnel system.
Kelly Wilkinson/IndyStar

Drawing board to construction

For those familiar with the project, it's hard to imagine the tunnel is actually underway, said Citizens spokesman Dan Considine, let alone opening soon.

"We've been talking about this project in the future tense for so long," he said, "but we've moved from the drawing board to construction."

Long before the first bulldozer treads left their mark or the first stick of dynamite was ignited, plans for the tunnel began in 2006 as part of a federal consent decree with the U.S. Environmental Project Agency, the Department of Justice and Indiana's Department of Environmental Management.

The goal: to clean up the city's waterways from the billions of gallons of sewage and storm wateroverflowing into them every year.

As bigger and older cities, such as Indianapolis, began to build up more than a century ago, sewers for flood control were one of the first systems to go in, according to John Trypus, director for Citizens' underground engineering and construction team. Not long after, cities connected sewers for waste to these pipes that dumped directly into rivers.

Although intercepts and improvements have been made over time, the combined sewer systems still overflowed more than five billion gallons annually just five years ago. That's more than 8,300 Olympic-sized swimming pools.

This is an improvement from the nearly eight billion gallons when the plan was originally created those 10 years ago, Trypus said, and more than 11 billion gallons in the 1990s.

Still, all it takes in Indianapolis is a quarter inch of rain to send waste out of one or more of the city's 134 overflow points, or outfalls, into the river.

"Wastewater that leaves your house will usually go to treatment plants, that is unless we get some rain," Trypus told IndyStar. "Rainfall is weird and certain clouds can dump in small areas and then all of a sudden we have 60 overflow events in your average year."

Residents should rest assured that the water is still cleaned and treated before it returns to their homes, but the waste can still be detrimental for plants and wildlife in and along the waterways, as well as render them useless for recreation.

Indianapolis is not alone: It is one of several hundred cities across the U.S. that have this type of legacy construction, as Trypus calls it. It also is one of several constructing similar tunnel projects to put a stop to the contamination — Washington, D.C., Columbus, Boston and Chicago among them.

At 109 miles of underground pipe, Chicago's system is the biggest in the world. Yet Indianapolis' tunnel has a few firsts of its own.

Untouched earth

More specifically: some world records.

In 2013, the project set three records for rock tunneling advancement with a tunnel boring machine — the first for most feet mined in a day, the second for most feet mined in one week and the last for most feet mined in one month.

At around 5,750 feet, the machine moved just more than one mile in May of that year. If that's the machine moving fast, then it's easy to see why construction on the tunnel — again, set to be 28 miles once completed — is a decade-long process in the making.

How could it not be, with tons of earth and rock standing in the way.

For every one foot that the machine grinds away and moves forward, it chews enough dirt to fill one whole dump truck. So for May 2013, that's more than 5,000 trucks. And for the first 11 miles set to open this month, more than 50,000 truckloads.

That rock needs to make its way from the machine through the miles of tunnel and up 250 feet to the surface, which takes tens of thousands of feet of conveyor belt.

The rock, however, is not alone in making that journey — so, too, do those who work to construct the tunnel.

With about a dozen workers underground at any given time, they must ride up and down in a small metal cage hoisted by a crane. Once below, workers still might have an hour-long commute on the "man mover" rail car to reach the machine depending how far into the tunnel the machine is.

Still, it's not as dark and musty as one might assume, Miller said.

Being a deep rock tunnel system, the machine often bores through and reveals interesting quartz formations that make the walls shimmer. Also, in various parts of the tunnel, it dissects two layers of earth that are more than 300 million years old.

"When you think about it," Miller said as he rested his hand on the distinct lines separating the different geologic layers in the tunnel's walls, "no one has touched this earth before."

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Michael Miller travels in a cage out from the tunnel of the Southport DRTC Pump Station, Monday, Sept. 11, 2017.(Photo: Kelly Wilkinson/IndyStar)

This particular machine has seen its fair share of rock and earth — being more than 40 years old. Its life began on the east coast working on subways. Before making its way to Indianapolis, however, the machine was remade and refit for this specific project.

Most cities choose to name their boring machines, Miller said, but Citizens Energy has chosen not to.

"There is a superstition in the tunneling world that if you name the machine," he said, "that it jinxes or dooms the project from the start."

Sewage solution

And perhaps that decision is paying off. The project is ahead of schedule.

When construction began on the Deep Rock Tunnel Connector in 2013, only the first nine miles were expected to be completed by now. But with the machine's smooth sailing, the two-mile Eagle Creek portion of the tunnel will also be coming online at the end of the month.

Between these two sections, they will catch just four of the more than 100 outfall points across the city. Still, two of those four overflow the most sewage and storm water across the entire system — with one at nearly 760 million gallons in the average year and the other around 460 million gallons.

Once the DRTC and Eagle Creek open, officials anticipate the overflows to drop to 2.5 billion gallons on average.

How? In addition to constructing the tunnel, Citizens must also build drop shafts that catch the waste before it releases into the waterways and instead diverts it to the tunnel, acting as a storage tank. A pump station at the south end of the tunnel then will lift the sewage and storm water to the utility's upgraded treatment plants.

Building and connecting those drop shafts is the precise reason Meridian Street will be closed from January to October, Considine said.

Construction includes two large sewers — 325 feet of 36-inch pipe and 560 feet of 60-inch pipe — designed to capture overflows and send them into the Fall Creek Tunnel. This portion of the DigIndy system is set for completion in 2025, according to Considine, along with the Pleasant Run tunnel.

Two other sections of the network — the White River and Lower Pogue's Run tunnels — are expected to come online in 2021.

When all is said and done, and the entire project comes to a close, only one or two overflows should happen each year in extreme events, releasing 220 million gallons of the contaminated water. That surpasses the 95 percent reduction goal, Trypus said.

"We anticipate overachieving a little bit," Miller added.

Bennett said he knows the Meridian and 28th street closures will likely be the most high-profile of all those related to the project..

"It will be a short-term pain," he said, "but the long-term gain is huge."

The deputy mayor has been around this project for many years, when the mandate from the federal government to clean the waterways was first looming. He has also been involved in many community development projects in his role and has lived along the polluted Pleasant Run.

To think of what the future holds, he almost gets giddy.

"By mid 2020s, which really is not too many years from now," Bennett said, "we will be at a point where (the White River) will be on its way to being the cleanest it's been for 150 years — now that's tremendous."

By the numbers:

409.89 — record for most feet mined in one day on May 10, 2013

1,690.04 — record for most feet mined in one week one June 10 to 14, 2013

Call IndyStar reporter Sarah Bowman at (317) 444-6129. Follow her on Twitter and Facebook: @IndyStarSarah. IndyStar's environmental reporting project is made possible through the generous support of the nonprofit Nina Mason Pulliam Charitable Trust.